Abstract

Surprising properties of doped Mott insulators are at the heart of many
quantum materials, including transition metal oxides and organic materials. The
key to unraveling complex phenomena observed in these systems lies in
understanding the interplay of spin and charge degrees of freedom. One of the
most debated questions concerns the nature of charge carriers in a background
of fluctuating spins. To shed new light on this problem, we suggest a
simplified model with mixed dimensionality, where holes move through a Mott
insulator unidirectionally while spin exchange interactions are two
dimensional. By studying individual holes in this system, we find direct
evidence for the formation of mesonic bound states of holons and spinons,
connected by a string of displaced spins -- a precursor of the spin-charge
separation obtained in the 1D limit of the model. Our predictions can be tested
using ultracold atoms in a quantum gas microscope, allowing to directly image
spinons and holons, and reveal the short-range hidden string order which we
predict in this model.

Current status:

Author comments upon resubmission

Dear Editors,

we would like to resubmit our paper “Meson formation in mixed-dimensional t-J models” to SciPost. We are grateful for the referees careful assessments, and after taking into account their recommendations and criticism, we believe that our work is now ready for publication. A detailed point-by-point response to the referee reports is provided in the pdf file uploaded in response to the referees.

Yours sincerely,Fabian GrusdtZheng ZhuTao ShiEugene Demler

List of changes

We have now added a reference to the recent paper [Chiu et al., arXiv:1810.03584] in the discussion at the end of our manuscript. To address a comment by the referee we have added a sentence in our manuscript on page 2: “We will confirm below, in Fig. 4, that the FSA is a reliable approximation.”In Fig. 2 b) we have now indicated explicitly in the figure caption the specific parameters.In Fig. 5 we have included an explicit reference to the Methods section now. We have also added an explanation in the caption of Fig. 9 in the Methods.On page 2 we have now clarified what we mean by geometric strings: “In the approximate set of basis states constructed so far this corresponds to a displacement of all spins along $\Sigma$, referred to as the geometric string, connecting $j_x$ and $j_x^s$.”We have included a sentence in discussion section now: “Our model Hamiltonian can be implemented at arbitrary doping levels using ultracold atoms in optical lattices.” To make the reader aware of the richness of our system at finite doping, we have included a remark on page 7 of our manuscript: “Note that the mixD Hamiltonian has many independent sectors of individually tunable doping levels per chain, which need to be studied separately.”